Defoaming agent for pulp and paper stock



Patented Aug. 14, 1951 DEFOAMIIN G AGENT FOR PULP AND PAPER STOCK Earl P. McGinn, Verona, N. 3., assignor to Nopco Chemical Company, a corporation of New Jersey No Drawing. Application October 12, 1945,

Serial No. 622,090

Claims. (01. 252-358) The present invention relates to defoaming and to the prevention of foam during paper manufacture and an improved defoaming agent for 0 paper stock. More particularly, the present invention relates to an improved composition and process for destroying and/or preventing foam, particularly during the manufacture of paper. In U. S. Patent No. 2,304,304, granted Decemher 8, 1942, there is disclosed a foam destroying composition comprising essentially a wax, preferably a mineral wax and a partial glyceride of a higher fatty acid. This composition is especially suitable for combination with a suspension of fibrous material and is effective to inhibit'foam production during the various stages of paper manufacture. I

Although this composition has proved commercially successful, it has been discovered in accordance with the present invention that the addition of a lower monohydric alcohol ester of a higher fatty acid to a composition otherwise in general similar to that described in the aforementioned patent, results in a greatly improved antifoaming agent. The exact function of the ester in the composition is not known, except that possibly the ester acts as a blending agent which is especially compatible with both the wax and the partial glyceride of the higher fatty acid. In any event, the improvement with the addition of the lower monohydric alcohol ester is surprising since, although some esters have been sug gested for preventing foam in casein compositions or the like, they are not in themselves good defoaming agents for paper stock.

It is one of the objects of the present invention, therefore, to provide a novel antifoaming composition especially suitable for preventing and I destroying foam in a paper pulp or fibrous material suspension.

Another object of the present invention is to provide a novel defoaming agent including a mineral wax, a small amount of an alkali metal soap of a fatty acid having at least 16 carbon atoms, a partial ester of a polyhydric alcohol and a higher fatty acid having at least 16 carbon atoms, and an ester of a fatty acid having at least 16 carbon atoms with a lower monohydric alcohol having not more than carbon atoms.

A third object of the present invention is to provide a novel process for defoaming paper stock weight.

which comprises adding to the heater or other paper-making machine a small amount of the aforementioned defoaming composition.

Other objects and advantages of the present invention will become apparent from the subse quent description and claims.

In general the composition of the present invention includes a mineral wax such as scale wax, although other mineral waxes, parafiins, microcrystalline wax, etc. may be used. Preferably, thiswax is present in the original paste-like composition as prepared for shipment in the proportion of 10-20% of the total composition by The composition may also contain a small amount of other waxes which serve to modify the nature of the mineral wax. Such a wax is candelilla wax, which has a substantially higher melting point.

In addition, there is formed in the composition during compounding thereof, a small amount of a soap of a higher fatty acid with an alkali metal. Such soap is present preferably in an amount equivalent to 4 to 7% of the composition. Preferably, the fatty acid used to form the soap contains at least-l6 carbon atoms and in general fatty acids of .from 16 to 22 carbon atoms are suitable for this soap formation. Any alkali metal soaps of the aforementioned fatty acids are suitable as, for example, sodium or potassium soaps. Examples of suitable soaps are potassium stearate, potassium oleate, potassium ricinoleate, sodium stearate, sodium oleate, etc.

The composition also contains from 5 to 2.3% of a partial ester of a polyhydric alcohol and a higher fatty acid. This higher fatty acid is preferably one having at least 16 carbon atoms and from 16 to 22 carbon atoms are suitable. fatty acid may be straight chain or branch chain and may be saturated, hydroxylated, etc. The expression partial ester is used herein to connote an ester of a polyhydric alcohol in which at least one of the hydroxylgroups remains free or unesterified. Suitable compositions of this type are glyceryl monooleate, ethylene glycol monostearate, ethylene glycol monooleate, diethylene glycol monostearate, diethylene glycol monooleate and mono esters of fatty acids with polyhydroxy alcohols such as sorbitol, mannitol, etc.

The present composition contains as a very essential ingredient an ester of a higher fatty acid having at least 16 carbon atoms and preferably from 16 to 22 carbon atoms with a lower monohydric alcohol. hydric alcohol" is used herein to connotean alcohol containing not more than carbon atoms and which contains only one hydroxy group. Of these esters, the highly preferred esters are the methyl esters of the aforementioned acids. These last esters have proved far superior to other esters, but in general, any monohydric alcohol ester where the alcohol has not more than 10 carbon atoms will be suitable. Preferably the monohydric alcohol ester forms from 5 to of the composition and approximately 10% is the preferred quantity. In producing the composition of the present invention, the wax and fatty acid which form the soap are first melted together. Thereafter, a sufficient quantity of concentrated alkali'is added and the whole mass stirred until homogeneous. Inasmuch as the saponification is exothermic, the temperature of the mass'during stirring will approximate about 60 C. Thereafter the partial ester of the polyhydric alcohol and fatty acid is added in molten form together with the ester of the monoliydric alcohol. of the dry ingredients are mixed, water is then added to make up 100% and agitation continued until a white homogeneous paste is formed.

The final paste when used is preferably diluted with water until the solid ingredients make up from 1 to 5% by weight of the diluted emulsion. It may then be added to the paper stock suspension so that the solids, just set forth, are present in an amount from 0.5 to 3.0 parts per million parts of stock suspension or from .01 to 2% of the dry fiber weight. This diluted emulsion may be added as needed to a paper-making machine such as a Fourdrinier or other machine and will be found to effectively inhibit the formation of foam. The amount of defoaming agent which is rethe process and other factors.

The following specific examples serve to illustrate but are not intended to limit the present invention.

'quired will vary with the type of water used in Example I 16 parts .by weight of scale wax, 1.6 parts candelilla wax and 5.6 parts of stearic acid were melted together. Thereafter, 2 parts of a solution of KOH were added and the whole mass stirred until homogeneous. The temperature during stirring averaged about C. 12 parts of glyceryl monostearate were melted in a separate container and mixed with 10 parts of methyl oleate. This last" mixture was then added to the wax-stcaric acid mix and stirred until clear. 52.8 parts of water at 40 to 60 C. were then added and agitation continued until a white homogeneous paste was produced. This paste was an excellent defoaming agent for paper stock and the like when added in the proportion of 1% to 10% by weight to 99% to 90% of water. 7 1

Example 11 The expression lower mono When the whole mess iii per second. A similar test made with a composition equivalent to that of Example 1, except that no methyl oleate was included, indicated that a rate of at least 0.133 gm./second was needed as at this rate bubbles were carrying all the way wax, from about 4 parts to about 7 parts by weight of an alkali metal soap of a fatty acid having from 16 to 22 carbon atoms selected from the group consisting of sodium soaps and potassium soaps of such fatty acids, from about 5 parts to about 20 parts by weight of a mono ester of a polyhydric alcohol and a fatty acid having from 16 to 22 carbon atoms,'and from about 5 parts to about 15 parts by weight of an ester of a monohydric alcohol containing from 1. to 10 carbon atoms with a fatty acid having from 16 to 22 carbon atoms, the balance of the emulsion being substantially all water and the amount of water in the emulsion not exceeding about 99% of the emulsion.-

2. A defoaming agent for pulp and paper stock comprising a .water emulsion made up of from about '10 parts to about 20 parts by weight of a mineral wax, from about 4 parts to about 7 parts by weightof an alkali metal soap of a fatty acid having from 16 to 22 carbon atoms selected from the group consisting of sodium soaps and potassium soaps of such fatty acids, from about 5 parts to about 20 parts by weight of a mono ester of a polyhydric alcohol and a fatty acid having from 16 to 22 carbon atoms, and from about 5 parts to about 15 parts by weight of a methyl ester of a fatty acid having from 16 to 22 carbon atoms, the balance of the emulsion being substantially all water and the amount of water in the emulsion not exceeding about 99% of the emulsion.

3. A defoaming agent for pulp and paper stock comprising a Water emulsion made up of from about 10% to about 20% by weight of a mineral wax, from about 4% to about 7% by weight of an alkali metal soap of a fatty acid having from 16 to 22 carbon atoms, from about 5% to about 20% by weight of a mono ester of a polyhydric alcohol and a fatty acid having from 16 to 22 carbon atoms, and from about 5% to about 15% by weight of an ester of a monohydric alcohol containing from 1 to 10 carbon atoms with a fatty acid having from 16 to 22 carbon atoms, the balance of the emulsion being substantially all u; ..ter.

4. A defoaming agent for pulp and paper tock comprising a water emulsion made up of from about 10% to about 20% by weight of a mineral wax, from about 4% to about 7% by weight of an alkali metal soap of a fatty acid having from 16 to 22 carbon atoms selected from the group consisting of sodium soaps and potassium soaps -of such fatty acids, from about 5% to about 20% by weight of a mono ester of a polyhydric alcohol and a fatty acid having from 16 to 22 carbon atoms, and from about 5% to about 15% by weight of a methyl ester of a fatty acid having from 16 to 22 carbon atoms, the balance of the emulsion-being substantially all water.

- 5. A defoaming agent for pulp and paper stock I comprising a water emulsion made up of about 16 by weight of scale wax, about 1.6 by weight of candelilla wax, about 12%-by weight of glyceryl monostearate, about 10% by weight of methyl oleate and the reaction product of about 5.6% by amass? weight of stearic acid and about 1% by weight of potassium hydroxide, the balance of the emulsion being substantially all water.

EARL P. McGIN'N.

summons c'rrm The following references are of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,563,857

Number Number Date I I 1. 23, 1944 Fritz Dec. 4, 1945 Wells July 1, 194': FOREIGN PATENTS Country Date France Nov. 7, 1935 OTHER REFERENCES Manufacture of Pulp and Paper, 3rd ed., vol. 5,

sec. 1, p. 101, published by McGraw-Hill Book Co.

Modern Papermaking by Clapperton et al., 1st

ed., published by Blackwell, Oxford, England (1929). D. 195.

Chemistry of Pulp and Papermaking, 3rd ed., by Sutermeister, published by John Wiley and EARL P. McGINN Sons (1941) Pp. 389 and 390.

August 1451951 It is hereby certified that error appears in the printed specificatidn of the above numbered patent requlrmg correctlon as follows:

Column 3, line 36, for 2% read 2%; column 4, line 48, after atoms and before the comma, insert selected from the and potassium soaps of such fatty acids;

group oomz'sting of sodium soaps and that .the said Letters Patent should be read as corrected above, so that the same may conform to the record of the 'case in the Patent Oifice.

Signed and sealed this 30th day of October, A. D. 1951.

THOMAS F. MURPHY,

Assistant Gammissz'oner of Patents. 

1. A DEFOAMING AGENT FOR PULP AND PAPER STOCK COMPRISING A WATER EMULSION MADE UP OF FROM ABOUT 10 PARTS TO ABOUT 20 PARTS BY WEIGHT OF A MINERAL WAX, FROM ABOUT 4 PARTS TO ABOUT 7 PARTS BY WEIGHT OF AN ALKALI METAL SOAP OF A FATTY ACID HAVING FROM 16 TO 22 CARBON ATOMS SELECTED FROM THE GROUP CONSISTING OF SODIUM SOAPS AND POTASSIUM SOAPS OF SUCH FATTY ACIDS, FROM ABOUT 5 PARTS TO ABOUT 20 PARTS BY WEIGHT OF A MONO ESTER OF A POLYHYDRIC ALCOHOL AND A FATTY ACID HAVING FROM 16 TO 22 CARBON ATOMS, AND FROM ABOUT 5 PARTS TO ABOUT 15 PARTS BY WEIGHT OF AN ESTER OF A MONOHYDRIC ALCOHOL CONTAINING FROM 1 TO 10 CARBON ATOMS WITH A FATTY ACID HAVING FROM 16 TO 22 CAR BON ATOMS, THE BALANCE OF THE EMULSION BEING SUBSTANTIALLY ALL WATER AND THE AMOUNT OF WATER IN THE EMULSION NOT EXCEEDING ABOUT 99% OF THE EMULSION. 